1. Field of the Invention
The present invention relates to a tape player for establishing a plurality of modes such as play and stop modes by moving a slider slidable along a chassis, and in particular to a lock mechanism for a slider for setting the modes.
2. Description of the Prior Art
Tape players have a mode in which one member should be brought into a pressure contact with another member.
For example, a tape loading post for pulling out a tape from a tape cassette to achieve a tape loading is brought into a pressure contact with a positioning block, or a pinch roller is brought into a pressure contact with a capstan so that a tape is pinched therebetween.
A limiter switch is usually used as a pressure contact means if such a pressure contact is necessary. In case of, for example, pressure contact of a pinch roller, a limiter spring is disposed between a movable member moved by a motor and the like and a support member for supporting the pinch roller thereon and spring biasing force is generated in the limiter switch by slightly moving the moving member by the motor even after the pinch roller is brought into a contact with the capstan so that the pressure contact therebetween is continued by the spring biasing force.
If the above-mentioned pressure contact has been achieved, members which are brought into a pressure contact by a biasing force of the limiter spring, for example, the above-mentioned pinch roller and a support member for supporting the same are applied with a reaction force due to the pressure contact, that is, a returning force. Accordingly, in order to keep the pressure contact condition, there is a need to provide the moving member or means for moving the same with some lock means to prevent the movement due to the returning force.
Various means have heretofore been used as such lock means. A worm gear is inserted into a rotation transmission system for transmitting the rotation of a motor to the moving member or, exclusively used electromagnetic actuators are comparatively often used for locking one of members of the transmission system.
The moving member for moving a support member which supports a member which is in a pressure contact with the other member often includes a mode establishing slider, that is, a slider which is rectilinearly slidably supported on a chassis and is moved to a given position to establish a given mode.
A considerable load is imposed upon the slider for moving the members to be in a pressure contact and the support member which supports these members and the transmission system of the slider drive unit for moving the slider under such a pressure contact condition. In a mode for achieving such a pressure contact with the tape, a suitable tension is usually applied to the tape and a strong force is applied to the tape in a depth direction on a position where the tape is pinched between the pinch roller and the capstan. Therefore, it is necessary to eliminate such a pressure contact for preventing components of the mechanism and the tape from being distorted and damaged due to high load imposed for an extended period of time when a power failure occurs in such a mode.
Accordingly, locking by said lock means is automatically released to release the pressure contact condition at least when a power failure occurs in a pressure contact condition.
Since an electromagnetic actuator is deenergized simultaneously with the power failure to release the lock condition in the case where the lock means for keeping the pressure condition includes the electromagnetic actuator, it is an advantage that special means for releasing the lock condition on power failure is not necessary. However, the electromagnetic actuator used as lock means is expensive so that the tape player cost is high.
In the case where a worm gear is used as lock means, rotation of a motor in the drive unit should be reversed for releasing the lock on power failure. It is necessary to additionally provide a capacitor having a comparatively high capacity as a back-up power supply for the reversal rotation. Therefore, this capacitor makes a control circuit more complicated and larger. There is also a problem that the tape player cost is high.